I'm inspecting the battlefield
The night before the battle. Before it's cluttered
With the debris of journalistic camp-followers

I feel that Hornbeck is referring to the courtroom when he mentions the battlefield. The battle that will be fought there is not the battle of soliders but the battle of Drummond and Brady. The night before the battle is referring to the night before the first day of trial. Before it's cluttered means when it is filled with the people. With the debris of journalistic camp-followers is referring to all of the towns people who want Brady to win this case because not teaching what is in the bible is "bad".